The Role of Green Beans and Tempeh in Boosting Vitamin B9, B6, and B12 Levels to Help Prevent Cleft Lip: A Scoping Review

Background: Cleft lip (CL), cleft palate (CP), and cleft lip and palate (CLP) are common birth defects, occurring in about 1 in 700 births, particularly in Asia and Indonesia. Vitamin deficiencies, especially B9, B6, and B12, during pregnancy are risk factors for CL. Mung beans, rich in vitamin B9, and tempeh, a plant-based source of vitamin B12, can help address these deficiencies as they promote healthy fetal development. Objective: This study evaluates the potential of mung beans and tempeh in increasing vitamins B9, B6, and B12 levels to prevent cleft lip. Method: We conducted a systematic search of the literature based on PRISMA (Preferred Reporting Items for Systematic Reviews and Meta-Analyses) and PICO criteria. Our inclusion criteria were: (1) studies discussing cleft lip or orofacial clefts; (2) studies evaluating the nutritional content of mung bean or tempe, particularly vitamin B9, vitamin B6, and vitamin B12; (3) articles published in English or Indonesian; (4) full original research articles available in complete text; and (5) publication year between 2015 and 2024. Articles without clear methodology, review articles, or studies not related to the targeted nutrients were excluded. Results: Thirteen articles published between 2015 and 2024 met the eligibility criteria for this scoping review. These studies originated from various countries, both developing and developed, and examined the nutritional content of mung bean and tempe as well as the roles of vitamins B9, B6, and B12 in craniofacial development. Eight studies emphasized the importance of maternal nutrition during pregnancy, identifying vitamins B9, B6, and B12 as key nutrients in preventing cleft lip and palate (CLP). These vitamins work together in the homocysteine and one-carbon cycles, which are essential for DNA synthesis and gene regulation during early facial development. Two studies highlighted the influence of epigenetic factors on CLP, noting that deficiencies in vitamin B9 or other maternal risk factors during weeks 4–8 of gestation can disrupt DNA methylation and interfere with normal lip formation. Three studies explored the nutritional benefits of mung bean and tempe. Mung beans were shown to be rich in vitamin B9 and B6, while tempe was identified as a plantbased source of vitamin B12. Evidence shows that consumption of mung bean flour can increase folate levels, supporting its potential role in reducing the risk of cleft lip. However, research on the direct impact of these foods on CL prevention is limited, highlighting the need for further studies. Conclusion: Vitamin B9, vitamin B6, and vitamin B12 play significant roles in embryonic craniofacial development, and deficiencies in these nutrients are associated with increased risk of cleft lip. Mung bean and tempe contain substantial amounts of these vitamins and therefore hold potential as affordable dietary sources to support maternal nutrition. However, current evidence remains limited regarding direct associations between consumption of these foods and cleft lip prevention. Further clinical and population-based studies are needed to confirm their preventive impact and to strengthen dietary recommendations for at-risk populations.